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Re: 68010 in a mac?

i mean maybe it will work but might not work with system 6 or something like that,, might just require system 7...?i don't know i have never done any testing.... cheap drop in solutions are always fun.

Re: 68010 in a mac?

I just caught this old post by trag from back in 08 :-)

Posted 28 March 2008 - 05:00 PMWhen Sun Remarketing was doing their liquidate-through-Ebay, I picked up five of the Brainstorm accelerators. I forget what I paid. Something like $15 each, I think. I picked up several because A) No one else was buying them and B) I had an eye toward reverse engineering them to learn something about how accelerators are built, and accidentally destroying the subject is a fine tradition in reverse engineering. That is also where all the new (unused) Mac Plus Mice came from. They sold boxes and boxes of them with 50 to the box. I picked up one and a smaller box of 20 or 30. Now I have more mice than I'll ever use in my attic. I am slowly reducing the supply through sales at $10 shipped within the USA.

Re: 68010 in a mac?

What's your goal for wanting to do this? I'll grant that the 68010 is "substantially" faster in a few areas (divide and multiply instructions, some loop operations, and increased speed when working with 32 bit longword quantities) but typically the observed system performance increase is only around 10% or so. (The 68010's "raison d'etre" was to fix the issue with the 68000 being incapable of working with virtual memory; the speed improvements were incidental.) Practically speaking I'd be sort of surprised if you even noticed the performance difference.

That said, well, if you're dying to try it it should be pin compatible so there shouldn't be any harm in just plugging it in and trying it; the question will be if the Mac ROM uses the "MOVE from SR" instruction in a manner incompatible with the 68010. (Said instruction is "privileged" on the 68010 but wasn't on the 68000.) This causes issues (which can be worked around with a patch) when sub-ing a 68010 into an Amiga, but... off the top of my head I'm *pretty* sure the original Mac always ran in Supervisor mode so the problem might never show up. It might be an interesting experiment, anyway.

(Do keep in mind that it's possible even if the well-known issue with the MOVE instruction doesn't show up there could be other issues. The Mac uses some really tight timing loops to, for instance, drive the IWM and it's possible the 68010 could introduce some subtle breakage there.)

Re: 68010 in a mac?

good point!I see the 68010 is 6 bucks, + 3 for shipping. i dunno it seems like a cheap experiment.but the goal would be to boost the plus speed if at all possible,,, Not talking about jamming ram into the side of itand having to pour liquid nitrogen on it, or anything like that. but 10% would be just fine, Mainly in good fun

Re: 68010 in a mac?

I think there's a good chance it would work. But if it did, you'd likely see little speed benefit, if any at all. My recollection is the one real speed improvement in the 68010 was some kind of special loop mode that functioned like a 1-instruction cache. But since none of the software you'd be running would take advantage of that feature, you wouldn't gain anything.

I've looked through the Mac Plus ROM quite a bit, and I'm pretty sure I never saw a move from SR instruction. So my hunch is you're safe there.

The IWM timing loops in the Plus ROM generally use polling to determine when to proceed to the next byte. As long as the 68010 is as fast as the 68000 (in clock cycles required per instruction), then I think you shouldn't have any trouble with that stuff either.

Re: 68010 in a mac?

I came across a 68010 in the early 1990s, and replaced my A500's CPU with it. Everything I could test showed no speedup, except for a several hour Sculpt3D render, which was faster by a little under 10 seconds. Probably within measurement error, that.

Re: 68010 in a mac?

Re: 68010 in a mac?

Danamania wrote:

I came across a 68010 in the early 1990s, and replaced my A500's CPU with it. Everything I could test showed no speedup, except for a several hour Sculpt3D render, which was faster by a little under 10 seconds. Probably within measurement error, that.

That makes sense, as far as I know the 68010 adds one new instruction and removes another, but doesn't make existing instructions any faster than they would be on a 68000.

Edit: It seems I may be wrong about this. It's hard to find any definitive information.

Re: 68010 in a mac?

Here's someone who did a bunch of performance testing on an Amiga 500, swapping the CPU between a 68000 and a 68010. Depending on the specific test, the '010 was anywhere from 0 to 11% faster than the '000. For most tests, the difference was either zero or just a few percent.

Re: 68010 in a mac?

I've order this processor : http://www.ebay.com/itm/281484739277 ,This 16mhz Toshiba is said to be pin compatible with the Motorola part. Instead of changing the crystal I may try a frequency doubler circuit.

Re: 68010 in a mac?

The macintosh portable, the E-clock is generated and synced through the main GLU. This allows Apple to get away with doubling the CPU clock. Otherwise, they couldnt do it unless they got away from the syncro bus.

What this means is, if you double the CPU frequency, You need to divide and generate your own E-clock and sync it up with the rest of the bus.

I was dealing with this thought when I was researching accelerators, Luckily there are schematics out there on accelerator boards that show how to deal with this scenario using some external glu logic.

You might be able to take the E clock on the 16Mhz CPU and pass it through a simple D-Flip-Flop, since technically if your using a PLL clock multiplier IC such as an IC511, everything is in sync phase locked anyway.

But this does present a small problem. If the RAM isnt running at 16Mhz with the processor, performance wont increase because if it takes 2 CPu clocks for every bus cycle, well... yea.

Re: 68010 in a mac?

Long ago Dr. Levinson and I used to do such hacks, and it worked about 80% of the time. Let me explain as per my memory.

As you know the 68010 has a few extra features no found in the 68000. A Tiny Cache of a few byte, extra opcodes and addressing modes. So it should run. Right? Well, 80% of the time it did.

On the many Dove-Board Macs we did this on, there were a couple we swapped the CPU on for the 68010. But like on the 8bit 6502 days, where some programmers used undocumented opcodes, the same with the Mac Programmers and the 68K on the 128/512K Macs. One such op-code dealt with the cache on the 68010, did something else on the 68000. It just so happened to be in the Font/DA's Calculator in the Apple Menu for System 3 to System 6, and it would crash the Mac hard! A couple of other programs also used this opcode and also crashed the Mac hard!

But once we figured out what programs and Font/DAs crashed the 68010 and removed them from the test machine, we figured that we could test it out. The 68010 beats the 68000, though this is just seconds shaved off minutes worth of various tests. Nothing big or major about this. But in things like SubLogic's Flight Sim, animation was smoother but not necessarily faster. The RAM Test was faster, especially when you had 2.5MB from the Dove Board, and it went through faster than a 512KB.

I wish I still had that list of what worked and what crashed on the Mac with the 68010. It would save a lot of headaches.

Re: 68010 in a mac?

He's decoupling the Video Subsystem of the Compacts in order to produce a higher resolution output. My question concerns the inverse: if standard video output is decoupled in the same manner and sync'd to the internal display, will overclocking the system bus to the point of FDD borkage become a possibility?